Is there really no way to control priority of workqueue processing as compared to user processes/threads?

Question

I've been reading a variety of references that discuss the use of bottom-half work queues for deferred processing in linux drivers. From what I glean, it seems like any work done by kernel work queues gets scheduled just like ordinary user processes/threads and that the only real difference between a kernel work queue-related process and a user process is that the work queue can move data between user-side buffers and kernel buffers. I would appreciate knowing if my interpretation of these references is correct, or whether there are mechanisms by which I can maintain some degree of control over the priority of work queue processing. More specifically, I'd like to know if I can guarantee that a work queue process has higher priority than any user process, at least when the work queue process is not sleeping. I'm asking this question in the context of handling reads/writes from/to chips hanging off a 400 kHz (i.e. slow) I2C bus. We're running linux 2.6.10 on an ARM9 processor. - Thanks!